Question

I am performing a fade effect on a button.

AnimationSet set = new AnimationSet(true);
Animation animation2 = new AlphaAnimation((float) 0, 1);
animation2.setDuration(1500);
animation2.setRepeatMode(0);
set.addAnimation(animation2);
set.setFillAfter(true); // leaves the animation in its final status
btn.startAnimation(set);

I am using the setFillAfter(true) option to leave the button visible. That works fine. Now I would like to perform the animation again, but can’t never set again my button to be invisible on the screen, unless I restart the app. (alos tried invalidate() with no success…)

Any idea would be “so” welcome.

Thanks in advance!
Paul

Answer 1

Thank you for you help. Actually I found the answer on the developpers doc. There is a big difference between “View animation” (which I tried to do) and “Property Animation”. Basically View animation redraws an image of the view you are working on, but does not affect the original view. So If you translate your view from example, on the screen the view is moved but programatically it remained in its initial state and will catch events in its original position.

Here is the explanation:

How Property Animation Differs from View Animation The view animation
system provides the capability to only animate View objects, so if you
wanted to animate non-View objects, you have to implement your own
code to do so. The view animation system is also constrained in the
fact that it only exposes a few aspects of a View object to animate,
such as the scaling and rotation of a View but not the background
color, for instance.

Another disadvantage of the view animation system is that it only
modified where the View was drawn, and not the actual View itself. For
instance, if you animated a button to move across the screen, the
button draws correctly, but the actual location where you can click
the button does not change, so you have to implement your own logic to
handle this.

With the property animation system, these constraints are completely
removed, and you can animate any property of any object (Views and
non-Views) and the object itself is actually modified. The property
animation system is also more robust in the way it carries out
animation. At a high level, you assign animators to the properties
that you want to animate, such as color, position, or size and can
define aspects of the animation such as interpolation and
synchronization of multiple animators.

The view animation system, however, takes less time to setup and
requires less code to write. If view animation accomplishes everything
that you need to do, or if your existing code already works the way
you want, there is no need to use the property animation system. It
also might make sense to use both animation systems for different
situations if the use case arises.

http://developer.android.com/guide/topics/graphics/prop-animation.html

For my case I used Property animation and it matches all my animation needs. Thank you for your support!
🙂

Paul